Priority is claimed to Japanese application No. 2002-345752, filed Nov. 28, 2003, which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a control apparatus for a fuel cell vehicle.
2. Description of the Related Art
A solid polymer membrane fuel cell conventionally comprises, for example, cells formed by sandwiching a solid polymer electrolyte membrane between a fuel electrode (anode) and an oxygen electrode (cathode), with a plurality of such cells arranged in a stack. Hydrogen is supplied to the fuel electrode as fuel, and air is supplied to the oxygen electrode as oxidant, and hydrogen ions generated by a catalytic reaction at the fuel electrode pass through the solid polymer electrolyte membrane and migrate to the oxygen electrode, causing an electrochemical reaction with the oxygen at the oxygen electrode, and generating electricity
As a fuel cell vehicle provided with such a fuel cell as a source of motive power, heretofore there is known a fuel cell vehicle, fitted with a capacitor comprising for example an electric double layer capacitor or an electrolytic capacitor or the like, and constructed so as to store the electrical energy generated by the fuel cell, and transfer electrical energy to the propulsion motor (see, for example, Japanese Unexamined Patent Application, First Publication No. 2001-357865).
In such a fuel cell vehicle, the capacitor is connected in parallel to the fuel cell via an output controller which controls the output current and output voltage of the fuel cell, and output control action such as chopping action or the like of the output controller which comprises, for example, a chopper type power conversion circuit, is controlled corresponding to the state of, for example, the fuel cell vehicle, the fuel cell, or the capacitor.
[Patent document 1] Japanese Unexamined Patent Application, First Publication No. 2001-357865
In practice, when starting a fuel cell vehicle according to the example of the aforementioned conventional technology, an air compressor or the like which supplies reactant gas to the fuel cell is driven by power supplied from the capacitor. Therefore, due to the fuel cell being connected directly to the capacitor for which the terminal voltage has dropped due to discharge, an excessive current flows abruptly from the fuel cell to the capacitor, and the terminal voltage of the fuel cell drops excessively. In order to prevent this, the current value of the output current extracted from the fuel cell is restricted by the output controller to a value less than a predetermined value, until the voltage difference between the fuel cell terminal voltage and the capacitor terminal voltage becomes less than a predetermined voltage difference including zero. Then the capacitor is charged with the output current from the fuel cell restricted to less than the predetermined value, and after the terminal voltage difference of the terminal voltages of the fuel cell and the capacitor becomes less than the predetermined value the restriction on output current is removed. In other words, the fuel cell and the capacitor are directly connected, after which drive power is supplied to the propulsion motor.
However, the capacitor for which the terminal voltage has dropped due to the discharge for starting the fuel cell is charged with power generated by the fuel cell, and movement of the vehicle is prevented until the voltage difference between the capacitor terminal voltage and the fuel cell terminal voltage is less than the predetermined voltage difference. Therefore, it is desirable to be able to begin movement of the fuel cell vehicle earlier.